Personal information for any particular user typically may be stored across multiple applications and services, with a user's access to such information being application-dependent, service-dependent, and generally tool-dependent, such that the user must (a) remember where (or by what) a given piece or collection of information is stored, (b) access the relevant application/service/tool, and only then is enabled to (c) access the desired information. Furthermore, similar but non-identical pieces of information for a particular user may be stored in multiple disparate applications/services/tools, so that any given application or service only provides part of such information.
For example, suppose that a user has posted family photographs on Service A (e.g., Facebook) but also uploaded other family photographs to Service B (e.g., Google+, Snapchat, Instagram, or any of a variety of other social media services). As long as the user's access to those photographs is dependent upon which particular service is being used, it may be difficult for the user to cohesively and coherently view all of her family photographs. Moreover, the manner in which those photographs may be viewed may be limited by the particular information service. Thus, by uploading or posting the photographs to those information services, she has ceded control of the manner in which she can view or modify them.
Such problems are compounded when considering the wide variety of information and types of information related to and stored for an individual by disparate devices, applications, services, and tools.
This fragmented nature of user information makes PIM (personal information management) difficult.